The common etiological agents of onychomycosis are dermatophytes, molds and yeasts. A mycological nail investigation of onychomycosis using direct microscopy and culture was conducted by the Mycology Unit, Department of Medical Microbiology, University of Malaya from March 1996 to November 1998. The study involved 878 nail clippings or subungal scrapings from subjects with onychomycosis. On direct microscopy examination, 50% of the specimens were negative for fungal elements. On culture, 373 specimens had no growth; bacteria were isolated from 15 nail specimens. Among the 490 specimens with positive fungal cultures, 177 (36.1%) were dermatophytes, 173 (35.5%) were molds and 130 (26.5%) were Candida. There were 2% (10/490) mixed infections of molds, yeasts and dermatophytes. Trichophyton rubrum (115/177) and Trichophyton mentagrophytes (59/177) were the main dermatophytes isolated. The molds isolated were predominantly Aspergillus niger (61/173), Aspergillus nidulans (30/173), Hendersonula toruloidea (26/173) and Fusarium species (16/173). 96.9% of the Candida species identified were Candida albicans.
The distribution of Candida species was examined using 1114 yeasts isolated from various clinical specimens. The isolates were identified by germ tube test, hyphal/pseudohyphae and chlamydoconidia production and carbohydrate assimilation test using ten carbohydrates (glucose, sucrose, trehalose, cellobiose, arabinose, galactose, mannitol, raffinose, lactose and maltose). Among the 1114 isolates studied, 9 species of Candida were identified and the relative frequency of isolation was C. albicans (44.2%), C. parapsilosis (26.0%), C. tropicalis (17.7%), C. glabrata (9.6%), C. krusei (1.2%), C. rugosa (0.6%), C. guilliermondii (0.2%), C. lusitaniae (0.08%) and C. kefyr (0.08%). Non-C. albicans was the most common Candida species isolated from blood, respiratory system, urine and skin. The isolate from vaginal swabs was predominantly C. albicans. 82.2% of C. glabrata and 64.2% of C. krusei isolated in this study were from vaginal swabs.